Many and his friends were comparing how much each of them grew last year. many grew 4 inches. jeff grew 1 1/2' times that amount
2 answers:
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Answer:
z = -3
Step-by-step explanation:
If we had two independent samples, the variance is known and and
are bigger than 30, the test statistic for the difference between the two population means is calculated as:
Where and
are the means of the samples,
and
are the variances of the samples and
and
are the size of the sample.
Finally, replacing by 82,
by 88,
by 112.5 ,
by 54,
by 45 and
by 36, we get that the statistic is equal to: